A symbiotic relationship between humans and pigs may have been what initiated their domestication, occurring as early as 10,000 B.C. in Thailand. Other sources place the time and place of domestication at 4900 B.C. in China. Sus scrofa may have used early gardens and garbage piles as food sources and humans took advantage of these pigs as a food source.
Sus scrofa has provoked mixed sentiments throughout history, from reverence to fear. In medieval Europe Sus scrofa was a popular carving in stone churches. They have also been regarded as a symbol of fertility and good luck. Others have not reacted so positively to Sus scrofa. Some saw the curly tail as connected to the devil. Jewish and Muslim traditions maintain strong taboos against the consumption of pork. Such adverse reactions may have originated because of the diseases associated with uncooked pork.
Domestic pigs are considered intelligent animals, more so than dogs. Circus trainers have characterized Sus scrofa individuals as quick learners with a substantial memory. Not only can they perform repetitive circus tricks, such as jumping through hoops and walking tightropes, but they can also solve simple problems such as opening a bolted door. Ivan Pavlov, the reknowned physiologist, first used pigs to perform some of his experiments, but eventually switched to dogs for reasons of temperament. It is also believed that Sus scrofa speaks a rudimentary language composed of calls, snorts, sniffs, and whistles.
Recently, Sus scrofa has been making the transition from an outdoor animal kept in the barn to an indoor pet. Miniature breeds have become popular pets.
(Hedgepeth, 1978; Hopf, 1979; vanLoon, 1979)
Smell is by far the most advanced of the pig's senses. A large round disk of cartilage is connected to muscle that gives the snout extra flexibility. Sus scrofa also has an advanced sense of taste. They are quick to identify unknown objects with their sense of taste. It is believed that Sus scrofa lacks good eyesight. The eyes are positioned on the sides of the head, restricting their forward vision. Pigs also vocalize, consisting mainly of grunts and squeals.
Communication Channels: visual ; tactile ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; chemical
Sus scrofa is not threatened in general. Populations of wild pig were exterminated through hunting from large parts of their native range, including the British Isles, Scandinavia, and Egypt. Reintroduction programs in Scandinavia seem to have been successful. Native pigs of the Ryukyu Islands (S. s. riukiuanus) are considered vulnerable as a result of excessive hunting. This subspecies is endemic to these islands, not an introduced feral population. There are numerous breeds of domesticated Sus scrofa, some of which seem to be in danger of disappearing and are the focus of domestic breed conservation efforts.
(Porter, 1993)
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
Sus scrofa carries parasitic infections transmissible to humans through eating undercooked pork and through contact, including trichinosis, cysticercosis, and brucellosis. Both domesticated and wild pigs are also quite aggressive and a surprising number of injuries results from interactions with pigs, primarily in domestic settings.
Introduced, feral populations of Sus scrofa are responsible for tremendous environmental damage worldwide. Their broad dietary habits, extremely destructive behaviors, and aggression make them one of the most destructive introduced species across the globe. Wild pigs destroy native vegetation as they dig for food, travel in herds, and create wallows. They will eat native animals, such as ground nesting birds and their eggs. Wild pigs may also act as crop pests.
Negative Impacts: injures humans (causes disease in humans ); crop pest; causes or carries domestic animal disease
Pigs are an integrated part of the diets of numerous human cultures. Pigs mature faster than other domesticated ungulates, have larger litters, and can feed on human garbage, making them efficient and valuable parts of many agricultural systems. Humans have taken advantage of their acute sense of smell for a variety of tasks. For instance, they have been used to find truffles, underground fungi used in French cuisine. In ancient Egypt they were used for "treading the seed." Their hoofs created holes perfect in size and depth for planting seeds. The Egyptians exploited this ability and used Sus scrofa extensively during planting seasons. Wild pigs (boars) are also hunted for sport. Miniature breeds of domestic pig have become popular as pets.
(Hopf, 1979)
Positive Impacts: pet trade ; food ; body parts are source of valuable material; produces fertilizer
In ecosystems in which pigs are native, pigs contribute to the diversity of systems by disturbing the soil - creating areas for new plant colonization, and by dispersing fruit seeds. Pigs, especially the young, are also an important source of prey for large predators. In ecosystems in which pigs are not native, they are extremely destructive, outcompeting native pigs and peccaries, damaging native vegetation, and preying on native animals.
Ecosystem Impact: disperses seeds; soil aeration
Sus scrofa is known for its omnivorous and sometimes indiscriminate diet. The diet includes fungi, tubers and bulbs, vegetation, grains and nuts, fruit, eggs, small vertebrates, invertebrates, carrion, and manure. Such a wide range of food sources has enabled Sus scrofa to survive in a variety of environments, from deserts to mountainous terrain.
(Hopf, 1979; Storer, 1992; Porter, 1993)
Animal Foods: birds; mammals; amphibians; reptiles; eggs; carrion ; insects; terrestrial non-insect arthropods; mollusks
Plant Foods: leaves; roots and tubers; wood, bark, or stems; seeds, grains, and nuts; fruit
Other Foods: fungus; dung
Primary Diet: omnivore
Of all members of the pig family, Sus scrofa occupies the largest range. They originally occurred in Europe, Asia, North Africa, and the Malay Archipelago. Included in this native range were a number of island populations, including the British Isles, Corsica, Sardinia, Japan, Sri Lanka, the Ryukyu Islands, Taiwan, Hainan, Sumatra, Java, and smaller islands of the East Indies. Sus scrofa was later introduced throughout the world as domesticated animals by humans. Currently, Sus scrofa can be found nearly everywhere, from homes to barns to boggy marshes and mountainous terrain.
(Hopf, 1979; Storer, 1992)
Biogeographic Regions: nearctic (Introduced ); palearctic (Native ); oriental (Introduced , Native ); ethiopian (Introduced ); neotropical (Introduced ); australian (Introduced ); oceanic islands (Introduced )
Other Geographic Terms: cosmopolitan
Although Sus scrofa is found in a wide variety of habitats as a result of domestication and introduction to new areas, the typical wild habitat is generally moist forests and shrublands, especially oak forests and areas where reeds are abundant. They are thought to be mainly limited by maximum winter snowfall, deep snow decreases their ability to travel and find food. They are sensitive to severe temperature changes. Sus scrofa has developed the technique of wallowing in mud or water to maintain a comfortable temperature. Wallowing also protects against sunburn and insect bites. Sus scrofa has even been known to wallow in their own urine to keep cool. Temperatures dropping below 50 degrees will cause discomfort. Conversely, Sus scrofa is prone to sunstroke in unusually warm temperature.
(Hopf, 1979; vanLoon, 1979; Storer, 1992)
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest
Other Habitat Features: suburban ; agricultural
Wild pigs usually live to about 10 years old, although some have been recorded living as long as 27 years. Mortality in the young is high.
Range lifespan
Status: wild: 27 (high) years.
Average lifespan
Status: wild: 10 years.
Average lifespan
Status: wild: 21.0 years.
Average lifespan
Status: wild: 20.0 years.
Wild boars are covered in a scant coat of coarse, bristle-like hairs ranging from dark gray to brown. Head and body length ranges from 900 to 1800 mm, tail length is about 300 mm, and shoulder height is 550 to 1100 mm. Weight averages 50 to 350 kg, though some domestic breeds can attain weights of 450 kg. Males are generally larger than females. Wild boar have four continually growing tusks, one in each quadrant of the jaw. Females have 6 pairs of mammae.
Over the course of domestication Sus scrofa has developed varying skin colors, tail lengths, and snout shapes. Sus scrofa has varying ear shapes, ranging from small and erect to low-flapping. Sus scrofa is thought to represent the primitive condition of ungulates in that they have a comparatively simple digestive system.
(Hopf, 1979; vanLoon, 1979)
Range mass: 50 to 350 kg.
Range length: 900 to 1800 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Average basal metabolic rate: 104.15 W.
The primary predator of mature wild pigs are humans. Mature pigs may also fall prey to very large predators, such as bears, large cats, and crocodiles. Young pigs may be preyed on by large snakes, raptors, cats, wolves, and other large predators. Pigs are extremely aggressive and bold when threatened. They use their ever-growing, sharpened tusks and the power of their bulk to charge and injure their attackers.
Known Predators:
Mating season is a violent time, as males often fight for access to females. Male Sus scrofa are able to continuously sharpen their tusks by rubbing the lower ones against the upper ones. The tusks are used as weapons most frequently during mating season. Sus scrofa individuals develop thick tissue around the front of the belly to help protect against stab wounds from tusks. The most aggressive males have been known to secure as many as eight sows during a single mating season.
Mating System: polygynous
In temperate regions females give birth to one litter in the spring. In tropical regions breeding occurs year-round but is often concentrated during moist seasons. Females have an estrous of about 21 days and are receptive for 3 days. Young are born after a gestation period of about 115 days (range 100 to 140). Mothers give birth to litters of from 1 to 12 young, generally between 4 and 8. Although sexual maturity can be reached between 8 and 10 months of age, females generally don't breed until 18 months old and males do not generally reach the size necessary to compete for females until 5 years old.
(Hopf, 1979)
Breeding interval: Females give birth to one to several litters in a year, depending on the region.
Breeding season: Breeding season is dependent on regional climate.
Range number of offspring: 1 to 12.
Average number of offspring: 4-8.
Range gestation period: 100 to 140 days.
Average gestation period: 115 days.
Range weaning age: 3 to 4 months.
Average time to independence: 7 months.
Range age at sexual or reproductive maturity (female): 18 (high) months.
Average age at sexual or reproductive maturity (female): 8-10 months.
Range age at sexual or reproductive maturity (male): 60 (high) months.
Average age at sexual or reproductive maturity (male): 8-10 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Average birth mass: 960 g.
Average number of offspring: 7.
Female Sus scrofa give birth to their young in a nest constructed of grass. The young remain in the nest for some time after birth. Females are extremely protective of their young. Despite these protective measures, on average only half of a litter will survive to maturity, many fall prey to predators and disease. Young are nursed for 3 to 4 months and generally become independent before the next litter is born (up to 1 year).
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Protecting: Female)
